Magnon dark modes and gradient memory

Abstract

Extensive efforts have been expended in developing hybrid quantum systems to overcome the short coherence time of superconducting circuits by introducing the naturally long-lived spin degree of freedom. Among all the possible materials, single-crystal yttrium iron garnet has shown up recently as a promising candidate for hybrid systems, and various highly coherent interactions, including strong and even ultrastrong coupling, have been demonstrated. One distinct advantage in these systems is that spins form well-defined magnon modes, which allows flexible and precise tuning. Here we demonstrate that by dissipation engineering, a non-Markovian interaction dynamics between the magnon and the microwave cavity photon can be achieved. Such a process enables us to build a magnon gradient memory to store information in the magnon dark modes, which decouple from the microwave cavity and thus preserve a long lifetime. Our findings provide a promising approach for developing long-lifetime, multimode quantum memories.

Strongly Coupled Nanotube Electromechanical Resonators

“…Using phonons as flying qubits is the first step in the exploration of multiple degrees-of-freedom electron-phonon systems. Possible future works would investigate CNT mechanical resonator arrays in phononic quantum memories [42], also many-body interactions [43] and the implementation of possible quantum error correction schemes in coupled spin-phonon chains [44]. This system can even be further integrated with superconducting circuits to construct a hybrid quantum machine [45,46].…”

Entangling two magnon modes via magnetostrictive interaction

“…This strong coupling offers a possibility to enable coherent information transfer between drastically different information carriers, and thus may find potential applications in quantum information processing, especially when the system becomes hybrid [10], such as by coupling magnons to a superconducting qubit [11,12], to phonons [13,14], or to both microwave and optical photons [15]. Furthermore, various interesting phenomena have been explored in the system of cavity-magnon polaritons, such as the observation of magnon gradient memory [16], the exceptional point [17,18], manipulation of distant spin currents [19], and bistability [20], to name but a few.…”

Ultrasmall Yttrium Iron Garnet Nanoparticles with High Coercivity at Low Temperature Synthesized by Laser Ablation and Fragmentation of Pressed Powders

“…[28] It is widely used as amaterial for microwave devices [29] and shows great potential in developingq uantum memories. [30] In nanoparticulate form, YIG gained the interest of researchers because of its potential applications in optical communication [31] and magneto-optical devices. [32,33] The smallest YIG nanoparticles, until now,w ere reported by Rajendran et al, [34] had an average size of 9nma nd were synthesized by aw et chemical approach.…”